Not to be a nerd, bug CrossOver is a Mac port of WINE, which recursively means Wine Is Not an Emulator. WINE/CrossOver are a set of native UNIX APIs reverse engineered from a subset of Windows APIs that allow Windiws apps to run natively in UNIX. This is similar to when Apple added Carbon APIs to OSX to run “Carbonized” classic Mac Apps natively alongside Cocoa apps. Apple basically “taught” OSX how to run those apps. WINE basically teaches UNIX how to run Windows apps.